A two-year-old Chihuahua was presented on day 58 of pregnancy due to very marked abdominaldistension. A cesarean section was performed and five normal and one clearly abnormal puppy were delivered.Examination of the abnormal puppy revealed a combination of congenital anomalies including epigastricheteropagus twinning. The autosite showed focal cranial aplasia cutis, anasarca, lissencephaly, palatoschisis,sternal agenesis and eventeratio (gastroschisis/schistocoelia). The partly formed parasitic twin was attachedat the sternal region of the autosite and demonstrated four formed limbs, atresia rectum, atresia ani, a singlekidney, tail agenesis and atresia vulvae. To the authors’ knowledge, this is only the third reported case ofheteropagus conjoined twinning in the dog and the first reported case of canine epigastric heteropagustwinning. In addition, there appear to be no reports in the veterinary literature noting an association withconjoined twinning in the dog with focal cranial aplasia cutis, eventeratio, lissencephaly, palatoschisis andanasarca. An in-depth literature review was hampered by the lack of a uniform nomenclature to identify thistype of conjoined twinning.